FBRC-ZSI-17, adult male, Venkatadri Hill, Tirumala Hill ranges (13.7066°N, 79.3644°E; 881 m a.s.l.), Seshachalam Biosphere Reserve, Tirupati District, Andhra Pradesh, India; collected by Deepa Jaiswal and Bharath B. on 16 December 2024.

FBRC-ZSI-18, male; FBRC-ZSI-19, male; and FBRC-ZSI-20, female; collection data same as holotype, collected on 17 December 2024. ZSI-R-28870, male, collection locality same as holotype, collected by Pratyush P. Mohapatra and Bharath B. on 6 October 2023.

ZSI-R-28871, juvenile, collection data same as ZSI-R-28870 (paratype).

Venkatadri slender gecko.

The specific epithet Venkatadri is a toponym for the type locality in the Tirumala Hill ranges in the Seshachalam Biosphere Reserve in Andhra Pradesh, India. The name Venkatadri is derived from two Sanskrit words: Venkata, meaning ‘one who removes sins’—one of the names of Lord Vishnu in the Hindu religion associated with the sacred Tirumala—and Adri, meaning mountain.

Hemiphyllodactylus venkatadri sp. nov. is characterized by a small adult body size (SVL 22.3–33.7 mm; n = 5), consistent with the generally slender habitus typical of the genus Hemiphyllodactylus. Diagnostic differentiation from congeners is instead based on the combination of morphological characters such as 12–16 chin scales; postmentals not enlarged; supralabials 9–12, infralabials 9–12; 16–18 dorsal scales, 9–16 ventral scales at mid-body are contained within one longitudinal eye diameter, 6–8 precloacal pores separated by 7–10 poreless scales from a series of 5–7 femoral pores on each thigh in males, lamellar formula of manus 2-2-2-2 and of pes 2-2-2-2; no plate-like enlarged subcaudals; color variable, dark longitudinal paravertebral markings on dorsum with two pairs of longitudinal stripes from nape to tail base insertions, the outer pair originating from behind the eye and inner pair from the nape; dark black streak passing from nostril to fore arm insertions; dorsal pattern with irregular dark lines and white spots; light and dark paravertebral spots on trunk; post-sacral spot with anteriorly projecting light colored bands; belly light mottled with black; one or two pairs of pointed cloacal spurs; dorsal part of the tail with 12 paired black-edged blotches forming bands.

Hemiphyllodactylus venkatadri sp. nov. can be distinguished from all other Indian congeners based on the combination of morphological characters provided in Table 3.

The holotype is in good condition, except for a small incision on the abdomen for tissue collection, tail attached to the body. Adult male, SVL 29.1 mm. Head slightly elongate (HL/SVL 0.26, HW/HL 0.66), slightly depressed (HH/HL 0.42), and distinct from neck (Fig. 4). Prefrontal region flat; canthus rostralis rounded, snout rounded in dorsal aspect (Fig. 4A). Snout short (SE/HL 0.40); slightly longer than eye diameter (ED/SE 0.55); scales on snout, canthus rostralis, forehead, and inter-orbital region homogenous in shape, granular; scales on the snout and canthus rostral slightly larger than those on occipital, forehead, and inter-orbital regions; 2–3 rows bordering supralabials flat and slightly elongated (Fig. 4C). Eye small (ED/HL 0.22); pupil vertical with crenulated margins; supraciliaries small, slightly mucronate, gradually increasing in size towards anterior of the orbit, those at the anterior end of orbit larger; ear opening unevenly oval (greatest diameter 0.4 mm), eye to ear distance larger than diameter of eye (EE/ED 1.47), undivided; single large supranasal above naris on each side, separated medially by three slightly smaller internasal scales; two postnasal on each side, marginally smaller in size than supranasals; rostral in contact with naris, supralabial I, supranasals and three small internasal scales; naris small, roughly round; external naris surrounded by supranasal, rostral, supralabial I and two postnasals on either side (Fig. 4C). Mental triangular, surrounded laterally by infralabial I on either side and posteriorly by three slightly enlarged chin scales; 7–8 scales touching internal edge of infralabials and mental from the juncture of 2^nd and 3^rd infralabials on either side (Fig. 4B, C). Labials large, supralabial I and infralabial I largest, gradually decreasing in size posteriorly; supralabials (to mid-orbital position) eight on each side; 9–10 supralabials (to angle of jaw) on each side; infralabials (to angle of jaw) 9–10 on each side.

Figure 3. 

Hemiphyllodactylus venkatadri sp. nov. (holotype, FBRC-ZSI-17). A. Dorsal view of body; B. Ventral view of body.

Figure 4. 

Hemiphyllodactylus venkatadri sp. nov. (holotype, FBRC-ZSI-17). A. Dorsal view of head; B. Ventral view of head; C. Lateral view of head; D. View of cloacal region showing precloacal and femoral pores.

Body moderately stout (BW/SVL 0.18), slightly elongate (TRL/SVL 0.52), ventrolateral folds indistinct. Scales on the dorsal side of the head and neck granular, slightly smaller than those on the snout and forehead; those on the dorsum slightly larger than the rest, flat, rounded, and sub-imbricate; 18 dorsal scales contained within one eye diameter. Ventral scales much larger than dorsal, smooth, imbricate, subcircular, gradually increasing in size posteriorly, except four or five rows above cloaca are much smaller; 15 scales contained within one eye diameter; gular region with smaller, granular scales, becoming slightly larger, flat, and juxtaposed on anterior aspect. Scales on palm and sole flat and rounded; scales on dorsal and ventral aspect of limbs flat and subimbricate, those on anteriolateral aspect of thigh largest. Fore and hind limbs short, stout; forearm short (FL/SVL 0.13); tibia short (CL/SVL 0.14). Digits with well-developed lamellar pads; digit I vestigial, without claw; digits II–V well developed, with free terminal phalanx arising from the lamellar pad, ending in an unsheathed, recurved claw; lamellar pads of all digits with basal series of undivided, transverse lamellae, expanding into large triangular apical lamellae, which are divided/deeply notched except terminal lamella, which is undivided; proximal lamellae/lamellar formula II–V: 2-2-2-2 (manus and pes); basal lamellae of digits II–V: 2-3-3-3 (manus) and 3-4-4-4 (pes); four transversely expanded lamellae on digit I (manus and pes).

Tail original (Fig. 3A, B), ventrally, forming caudal segments; tail shorter than snout-vent length (TL/SVL 0.75); similar-sized postcloacal spurs on both sides. Angular series of six precloacal pores separated from a series of seven femoral pores on each side by 10 (left) and nine (right) poreless scales (Fig. 4D).

(Figs 3, 5). The dorsum is of mottled brown to grey with irregular speckling, head, and limbs of the same color with scattered light and dark markings; a lighter pre-orbital stripe and two distinct dark postorbital stripes extend beyond forelimb insertions; dark diagonal markings on the flanks forming a criss-cross pattern and with light spots in between the reticulations; forelimbs and hind limbs with light-colored scattered spots. Post-sacral region with typical chevron-shaped mark with faint extended lines towards the anterior end, extending above hindlimb insertions, and aligns with the series of light spots along the dorso-lateral lines; more than 10 prominent chevron-shaped markings on the dorsal part of the tail with wavy dark brown to cream bands. Ventrally, the belly light mottled with black, the throat stippled with dark spots and numerous dark scales, precloacal region with pigmentation of light cream color; the ventral side of the tail orangish-red.

Figure 5. 

Holotype (FBRC-ZSI-17) of Hemiphyllodactylus venkatadri sp. nov. in life.

Faded ground color of dorsum; dorsal patterned with irregular dark lines; head and limbs pale-brown with scattered light markings; indistinct dark pre-orbital stripe; two distinct dark postorbital stripes up to forelimb insertions; clear dark longitudinal paravertebral markings on dorsum; indistinct dark reticulations enclosing white spots along the dorsolateral aspect of body; a pair of indistinct paravertebral stripes on nape, light or light-colored scattered light cream spots on anterior side of arms. Post-sacral marks divided with pale dark brown and cream white; tail brown with 10–12 pairs of indistinct black crossbars, posterior to post-sacral marking; ventral body paler, mottled with black; throat and outside of belly off-white, stippled with clear dark spots; ventral side of tail orangish, which gradually fades.

Mensural and meristic data for the type series are given in Table 3. There are three male and one female paratypes ranging in size from 22.3–33.7 mm. All paratypes resemble the holotype except as follows: three paratypes, FBRC-ZSI-18 (with a detached tail), FBRC-ZSI-20 and ZSI-R-28870 are with regenerating tail; FBRC-ZSI-19 with original and complete tail, slightly shorter than the body (TL/SVL 0.51); FBRC-ZSI-18, with completely regenerated tail, more than half of the body (TL/SVL 0.69).

The species shows ground color and pattern variations and are quick to change their color (Figs 5, 6). The extent of the postsacral marking is also variable; tail 10–12 pairs of dark brown to cream bands on dorsal, orange-brown, orange or light orange and orange ventrally.

Figure 6. 

Paratype (FBRC-ZSI-18) of Hemiphyllodactylus venkatadri sp. nov. in life.

Hemiphyllodactylus venkatadri sp. nov. shows 9.9–11.7% divergence in uncorrected pairwise p-distances of ND2 sequence data from other peninsular Indian congeners, the closest being H. jnana, H. nilgiriensis, H. peninsularis, and the undescribed H. sp. IN 5. This species was included in Agarwal et al. (2019) as Hemiphyllodactylus sp. IN 6. Hemiphyllodactylus venkatadri sp. nov. forms a separate subclade sister to the group comprising H. jnana, H. nilgiriensis, H. peninsularis, and the undescribed species labelled as H. sp. IN 5 in Agarwal et al. (2019).

Hemiphyllodactylus venkatadri sp. nov. is currently known only from its type locality in the high-elevation forests of Venkatadri Hills, Seshachalam Biosphere Reserve, Andhra Pradesh. Extensive rapid surveys undertaken across other hill ranges within the Seshachalam Biosphere Reserve did not yield any records of Hemiphyllodactylus species during the study period. The holotype was collected in a sandalwood (Santalum album Linnaeus) plantation. The habitat in the collection locality comprises a patch of grassland surrounded by tropical dry deciduous forest with moist deciduous patches and scrubland (Fig. 7). The holotype and the paratypes were collected under the bark of Diospyrus melanoxylon Roxburgh trees within a radius of 30 meters during daytime (1200–1620 hrs) at a height of 1.5–3 m above the ground. Other arboreal geckos inhabiting the area include Hemidactylus cf. parvimaculatus Deraniyagala, 1953, Hemidactylus rishivalleyensis, and Cnemaspis avasabinae.

Figure 7. 

Habitat of Hemiphyllodactylus venkatadri sp. nov. in Venkatadri Hill, Andhra Pradesh. A. Habitat type; B. Undergrowth vegetation.